The sum of two numbers is $27$, and their difference is $7$. What are the two numbers?
Let $x$ be the first number, and let $y$ be the second number. The system of equations is: ${x+y = 27}$ ${x-y = 7}$ Solve for $x$ and $y$ using elimination. Add the top and bottom equations together. $ 2x = 34 $ $ x = \dfrac{34}{2} $ ${x = 17}$ Now that you know ${x = 17}$ , plug it back into $ {x+y = 27}$ to find $y$ ${(17)}{ + y = 27}$ ${y = 10}$ You can also plug ${x = 17}$ into $ {x-y = 7}$ and get the same answer for $y$ ${(17)}{ - y = 7}$ ${y = 10}$ Therefore, the larger number is $17$, and the smaller number is $10$.